After Android M, Google also talked a lot about Google Now - which is getting a major upgrade called Now on Tap. In short, Now on Tap is context-aware, and knows what's going on in the application you're using right now. If someone sends you a WhatsApp message that says "Want to have dinner at Chez Fred tonight?", you can bring up a Google Now overlay without leaving WhatsApp that shows you a Google Now card with information pertaining to Chez Fred. Or, if you're listening to a song on Spotify, you can just say "OK Google, who's the lead singer", and Google Now will provide the answer.

We're working to make Google Now a little smarter in the upcoming Android M release, so you can ask it to assist you with whatever you're doing - right in the moment, anywhere on your phone. With "Now on tap," you can simply tap and hold the home button for assistance without having to leave what you’re doing - whether you're in an app or on a website. For example, if a friend emails you about seeing the new movie Tomorrowland, you can invoke Google Now without leaving your app, to quickly see the ratings, watch a trailer, or even buy tickets - then get right back to what you were doing.

Developers do not have to do anything to their applications to make them work with Now on Tap - they only need to be indexed by Google.